Case IH 3735 (DTC 8355) - ECU – Engine Control Unit (ECU): Fuel metering unit has an over-temperature error

The control module has detected the metering unit's electrical circuit is operating above safe temperature thresholds. This is typically caused by excessive current draw, a short circuit, a failing internal solenoid coil, or an improper external power supply.

• MAXXUM T4E
• 240 Series Axial-Flow Combines (7240, 8240, 9240)
• Case IH Puma Series
• Case IH A8000 and A8800 Sugar Cane Harvesters

1. 1

   Check for concurrent fault codes: If other fuel-related faults are active (specifically 3301 / DTC 1565 'Fuel rail pressure has exceeded maximum negative deviation limits'), diagnose and resolve those first

2. 2

   Check external power supplies: Verify that the machine's battery has not been connected to an external power supply like a high-voltage jump starter or improper charger

3. 3

   Inspect low-pressure fuel lines: Check the lines running from the fuel tank to the high-pressure pump for any damage, kinks, or clogging

4. 4

   Check lift pump pressure: Verify that the gear pump (low-pressure lift pump) is delivering proper fuel pressure to the metering unit

5. 5

   Inspect wiring: Check the wiring harness and connector at the fuel metering unit for chafing, shorts to ground, or corrosion that could cause high electrical resistance and overheating

1. 1

   Prepare machine and clean area

   Turn off the machine, remove the key, and allow the engine to cool. Clean the area around the high-pressure fuel pump thoroughly to prevent debris from entering the fuel system.

2. 2

   Disconnect electrical harness

   Disconnect the electrical harness connector from the fuel metering unit on the high-pressure pump.

3. 3

   Remove mounting screws

   Remove the mounting screws (typically Torx or Allen head) securing the metering unit to the pump housing.

4. 4

   Remove metering unit

   Carefully pull the metering unit out of the pump.

5. 5

   Lubricate O-rings

   Lubricate the O-rings on the new fuel metering unit with clean diesel fuel or approved assembly grease (e.g., Case IH Akcela Moly Grease).

6. 6

   Insert new metering unit

   Insert the new metering unit into the pump housing, ensuring the O-rings are not pinched.

7. 7

   Install mounting screws

   Install and torque the mounting screws to OEM specifications.

8. 8

   Reconnect electrical harness

   Reconnect the electrical harness.

9. 9

   Clear fault codes and verify

   Use the Case IH Electronic Service Tool (EST) to clear the fault codes and verify the status of 3735 (DTC 8355). Run the engine to ensure normal operation and check for leaks.